Bioinspired, Tree‐Root‐Like Interfacial Designs for Structural Batteries with Enhanced Mechanical Properties

Abstract

a multifunctional component in vehicles, which serves as both a power source and a structural component. [10][11][12][13] Hence, the total vehicle weight is expected to be reduced due to the mass reduction of structural components, such as car frames and airplane wings.This "structural battery" concept has drawn increasing attention in recent years, and it has been discussed by leading electric vehicle companies lately. [14,15] The key requirement of structural batteries is enhanced mechanical properties, such as strength, modulus, and robustness under different kinds of mechanical deformation (e.g., shearing, flexing, compression, and tension). Strategies to enhance mechanical properties have been explored at both system and material levels. At the system level, cells were integrated with external supporting materials with high strength, such as metals and carbon fiber (CF)-based fabric, to form better mechanical configurations like sandwich structures and strengthen the battery systems. [16][17][18] However, this strategy inevitably results in lower energy densities because of the extra components for reinforcements, and reported reductions are in the range of 40-95%. [16][17][18] At the material level, the underlying principle is to develop new multifunctional materials, which not only function as necessary components in a battery, but also provide enhanced mechanical properties. These materials range over all components in a battery, such as active electrode materials, electrolytes, binders, and substrates. [19][20][21][22] For example, various groups demonstrated that carbon fibers, which have been widely used for load carrying, can serve as the anode itself or the cathode current collector for structural batteries. [23][24][25][26] However, the cycling performance of carbon fibers is not satisfactory, and lithiation dramatically weakens the mechanical properties of carbon fibers. [27,28] Moreover, it is difficult to integrate carbon fibers and cathode materials densely, so the cell energy density is severely compromised. Besides electrode materials, mechanically strong aramid fibers have been explored as the separator, which remarkably enhances both safety and tensile strength of structural batteries, but the cell's capacity and cycling stability are sacrificed considerably. [29] Among different mechanical properties to enhance, flexural properties are especially important, since bending is one of the most common mechanical deformations in cars and aircraft.Structural batteries are attractive for weight reduction in vehicles, such as cars and airplanes, which requires batteries to have both excellent mechanical properties and electrochemical performance. This work develops a scalable and feasible tree-root-like lamination at the electrode/separator interface, which effectively transfers load between different layers of battery components and thus dramatically enhances the flexural modulus of pouch cells from 0.28 to 3.1 GPa. The underlying mechanism is also analyzed by finite element simulations. Meanwhile,...

Lithium metal structural battery developed with vacuum bagging

“…As shown in Table S1 (ESI†), the mechanical properties of the LMSB prepared in this work are highly competitive with those of structural batteries reported previously. 3,6,10,35–37 Obviously, the LMSB developed is effective as a dual-functional component to withstand loads and store electrical energy simultaneously.…”

Learn from nature: Bio‐inspired structure design for lithium‐ion batteries

“…100 In order to prevent sliding effect inside structural batteries, Yang et al reported robust interface between electrode and electrolyte inspired by tree roots, which can stabilize soil and trees against external wind force (Figure 4A). 101 The tree and soil correspond to electrolyte and electrode layers, and the wind force is an analog to shear force caused by deformations. The deep and strong roots provide excellent mechanical stability to hold soil against external forces.…”

“…(A) Bio‐inspired tree‐root‐like interfacial designs. Reproduced with permission: Copyright 2021, Wiley‐VCH 101 . (B) Bio‐inspired polysulfide adsorptive brush for battery interface design.…”

Experimental and computational characterization of carbon fibre based structural battery electrode laminae

“…This type of material can be used in lithium-ion (Li-ion) based structural batteries, i.e. batteries with mechanical load-bearing capability [1,2,[4][5][6][7][8][12][13][14][15], in electrochemical actuators [16], or in energy harvesting and strain sensing composites [17][18][19]. Due to the multifunctional character of such material, it offers a promising material choice for innovative future design of electric vehicles [6] and devices (e.g.…”

“…Due to the multifunctional character of such material, it offers a promising material choice for innovative future design of electric vehicles [6] and devices (e.g. laptops and phones) [20], as well as autonomous robotics [10], unmanned aerial vehicles [9,15] and satellites. In structural batteries, the carbon fibres can function as combined active electrode material, current collector and mechanical reinforcement.…”